Reversing devices for sheets of paper are known. U.S. Pat. No. 4,456,236, for example, describes a reversing device used to enable duplex paper sheets, after they have been taken through a scanner, to be fed with the opposite side through the scanner via a looped guide. A roller system rotatable in two directions is disposed directly downstream of the scanner. A deflecting structure is located between the roller system and the scanner and is formed by an elongate guide member which forms the paper sheet guide in the first part of the looped inverting path. The deflecting structure is disposed rotatable about a fixed pin,, and forms the actual deflector by the downwardly hanging end. This downwardly hanging end usually extends as a result of gravity within the path taken by a duplex paper sheet after it has just been scanned for the first time and is fed through the nip. The sheet of paper forces the downwardly hanging end of the guide part up out of the associated path. After the trailing edge of the paper sheet has passed the downwardly hanging end of the guide part, the part will again fall under the influence of gravity. The drive rollers are then rotated in the opposite direction so that the trailing edge of the paper sheet becomes the leading edge. This leading edge extends above the downwardly hanging end of the guide part and will be forced obliquely upwards by the guide part in order to pass through the looped path.
This known inverting device is operated by the product being treated and by the dead weight of the guide part. As a result, the reliability of the known device is not always sufficient and the device is susceptible to trouble as a result of the considerable risk that paper sheets will jam. Also, the guide part can readily damage the paper sheet moving past it and/or an image on the paper sheet.